When an oil well is being drilled, drilling personnel may encounter an unexpected high pressure situation requiring them to install a safety valve into the top of the drill pipe or tubing, from which uncontrolled high pressure fluids and gases are flowing.
Various methods are presently used to attempt such installation. The methods share a common feature of positioning the safety valve over the drill pipe while the valve is suspended by a cable, chain or rope catline. Typically, drilling personnel are required to physically align the end of the safety valve (which can weigh from 50 to 300 pounds) with the top of the drill pipe (which may be 5 to 10 feet off the working floor), while fluids and gases are escaping. If flowing pressures do not exceed 50 psi, the present methods can be successful. However, higher pressures can result in serious injury to personnel, either by movement of the suspended safety valve or impact from blown fragments of sand and gravel. If a safety valve cannot be installed, the only recourse is to allow the blowout to continue until the pressurized fluids are exhausted, or until the formation collapses, with detrimental environmental repercussions.
In U.S. Pat. No. 6,189,620, this inventor described an apparatus for installing a safety valve. In U.S. Pat. No. 6,488,094, this inventor described a similar apparatus with an improvement for stabilizing the hydraulic unit in extremely high pressure situations.
The present invention is directed to overcoming the problems associated with installing a suspended safety valve when the drilling or workover rig floor is not level.